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CreateNURBSSurface Method (Int32, Int32, IList(Double), IList(Double), IList(XYZ), IList(Double), Boolean, BoundingBoxUV)

Construct BRepBuilderSurfaceGeometry based on NURBS surface data, where the weights are supplied. In this case, the NURBS surface will be a piecewise rational polynomial surface.

Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 17.0.0.0 (17.0.1090.0)
Since: 2016

Syntax

C# 
public static BRepBuilderSurfaceGeometry CreateNURBSSurface(
	int degreeU,
	int degreeV,
	IList<double> knotsU,
	IList<double> knotsV,
	IList<XYZ> controlPoints,
	IList<double> weights,
	bool bReverseOrientation,
	BoundingBoxUV surfaceEnvelope
)
Visual Basic 
Public Shared Function CreateNURBSSurface ( _
	degreeU As Integer, _
	degreeV As Integer, _
	knotsU As IList(Of Double), _
	knotsV As IList(Of Double), _
	controlPoints As IList(Of XYZ), _
	weights As IList(Of Double), _
	bReverseOrientation As Boolean, _
	surfaceEnvelope As BoundingBoxUV _
) As BRepBuilderSurfaceGeometry
Visual C++ 
public:
static BRepBuilderSurfaceGeometry^ CreateNURBSSurface(
	int degreeU, 
	int degreeV, 
	IList<double>^ knotsU, 
	IList<double>^ knotsV, 
	IList<XYZ^>^ controlPoints, 
	IList<double>^ weights, 
	bool bReverseOrientation, 
	BoundingBoxUV^ surfaceEnvelope
)

Parameters

degreeU
Type: System Int32
The degree of the spline in the u-direction; must be positive.
degreeV
Type: System Int32
The degree of the spline in the v-direction; must be positive.
knotsU
Type: System.Collections.Generic IList Double
Knot values in the u-direction. The number of knots in the u-direction must be at least 2 * (degreeU + 1).
knotsV
Type: System.Collections.Generic IList Double
Knot values in the v-direction. The number of knots in the v-direction must be at least 2 * (degreeV + 1).
controlPoints
Type: System.Collections.Generic IList XYZ
One dimensional array of points representing the two dimensional net of control points of the NURBS surface in u and v directions.

The total number of control points must equal numControlPtsU times numControlPtsV, where numControlPtsU and numControlPtsV are the numbers of control points in u and v directions, and they must satisfy the following conditions:

  • numControlPtsU = number of knots in u - degreeU - 1.
  • numControlPtsV = number of knots in v - degreeV - 1.
The convention for 2d (idxU, idxV) to 1d (idx) conversion of array indexes: idxV first. That is, idxU is outer loop and idxV is inner loop. In other words, idx = idxU * numControlPtsV + idxV.

weights
Type: System.Collections.Generic IList Double
Array of weights assigned to the control points. The number of weights must equal the number of control points. All weights should be greater than zero.
bReverseOrientation
Type: System Boolean
If true, the surface's orientation is opposite to the canonical parametric orientation, otherwise it is the same. The canonical parametric orientation is a counter-clockwise sense of rotation in the uv-parameter plane. Extrinsically, the oriented normal vector for the canonical parametric orientation points in the direction of the cross product dS/du x dS/dv, which S(u, v) is the parameterized surface.
surfaceEnvelope
Type: Autodesk.Revit.DB BoundingBoxUV
Envelope of the surface in the uv parametric domain. Defines the domain of interest for the created surface. This is typically used to identify the domain of the face that references the surface in question. Expected to either be null or define a valid domain.

Remarks

A rational polynomial is a quotient of two polynomials; this includes a polynomial, which can be thought of as a quotient with denominator equal to 1. If all the weights are equal, then the NURBS surface will be a piecewise polynomial surface.This class does not handle periodic Nurbs surfaces.

Exceptions

Exception Condition
Autodesk.Revit.Exceptions ArgumentException The U-degree value must be at least 1. -or- The V-degree value must be at least 1. -or- The number of knots in the U direction must be at least 2 times the U-degree plus 1. -or- The number of knots in the V direction must be at least 2 times the V-degree plus 1. -or- The number of control points must equal (number of U-knots - U-degree - 1) * (number of V-knots - V-degree - 1). -or- The number of weights must be the same as the number of control points and all weights must be positive or all zero. -or- The input data does not define a valid Nurbs surface.
Autodesk.Revit.Exceptions ArgumentNullException A non-optional argument was NULL
Autodesk.Revit.Exceptions InvalidOperationException The Nurbs surface could not be converted for use in Revit. It may have C2-discontinuities or be too large.

See Also